Octupole deformation in even-even Rn-Th nuclei

The ground-state properties and high-spin spectra of the light even-even Rn-Th nuclei have been systematically investigated using the cranking shell model in a multidimensional deformation space, including ??2, ??3, ??4 and ??5 degrees of freedom. Calculations reproduce well the experimental values of the moment of inertia. The investigation of the structures shows that, with increasing neutron number, the ground-state shapes of these nuclei evolve from nearly spherical (N approximately equals 130), through well-developed octupole (N approximately equals 136) to well-deformed quadrupole (N greater than or equal 140) shapes. Cranking calculations display that the nuclei investigated are very octupole soft and will restore to reflection-symmetric shapes at high spin.EI0SUPPL. 278-803